refs #325, as preparation to reduce loading I need to find out when an info area is visible.

Existing functions visible() / isHidden() are not suitable, as those represent "technical visibility".
We need a logical visibility telling us if the user can see / has selected the corresponing dockable widget.

* New base class info area (where dockable widgets are placed)
* Adjusted derived component (currently 1)
* Cleaned up old code in floatAllWidgets

src/blackgui/dockwidgetinfoarea.h

@@ -16,8 +16,13 @@
 
 namespace BlackGui
 {
+    //! Forward declarations
+    class CInfoArea;
+    namespace Components { class CDockWidgetInfoAreaComponent; }
 
-    //! Class for dock widgets serving as info bar
+    //! Specialized class for dock widgets serving as info area
+    //! \sa CDockWidgetInfoBar
+    //! \sa CInfoArea
     class CDockWidgetInfoArea : public CDockWidget
     {
         Q_OBJECT
@@ -26,9 +31,28 @@ namespace BlackGui
         //! Constructor
         explicit CDockWidgetInfoArea(QWidget *parent = nullptr);
 
+        //! The parent info area
+        const CInfoArea *getParentInfoArea() const;
+
+        //! The parent info area
+        CInfoArea *getParentInfoArea();
+
+        //! Is this the selected widget, means it is not floating, and the one selected
+        bool isSelectedDockWidget() const;
+
+        //! Visible widget
+        bool isVisibleWidget() const;
+
     protected:
         //! Contribute to menu
         virtual void addToContextMenu(QMenu *contextMenu) const override;
+
+        //! \copydoc CDockWidget::initalFloating
+        virtual void initalFloating() override;
+
+    private:
+        //! Find all embedded runtime components
+        QList<Components::CDockWidgetInfoAreaComponent *> findEmbeddedDockWidgetInfoAreaComponents() const;
     };
 
 } // namespace